When Nobina, the largest public transport provider in the Nordic countries added hybrid electric buses to its bus fleet, it became imperative to understand their in-service behaviour, especially when bearing in mind the sheer volume of passengers that rely on the service and thousands of kilometres travelled per day.

It is for this reason that Nobina has taken the unusual step of employing a control systems expert as Operating Engineer for Nobina’s Electric Vehicles. Typically, in-depth software and hardware expertise aren’t top of the list for new recruits of a bus company, but Mattias Rosengren’s new position might well change that view!

Nobina’s hybrid buses use a parallel electric powertrain coupled to a standard diesel engine. The lithium battery enables the buses to drive in full electric mode from standstill up to 20 km/hr, while electronic features such as a stop-start system, that cuts off the engine when the bus is stationary, provide fuel consumption efficiencies and lower carbon emissions.

“By accessing the vehicle’s controller area network (CAN), useful information can be gleaned by data logging systems from the tens of connected ECUs that make up the bus’s electronic control system, such as the engine, transmission, electronic stability and battery management systems.”

Whether it is the analysis of charging cycles, monitoring driver behaviour or examining battery health, there are plenty of ways in which this data can be used to optimise vehicle efficiency, for the benefit of the environment and the company’s ‘bottom line’. Another reason for introducing logging capabilities is safety. Safety-related incidents and driver claims, or intermittent faults caused by individual components, can all be investigated by placing a data logger on the vehicle’s electronic network for an extended period and evaluating the results.

Rosengren has put together a test toolchain to study the performance of Nobina’s electric bus fleet and plans to expand the program to the associated charging infrastructure. He explains: “We use an open source engineering tool to simulate, analyze and test data bus systems, as well as Kvaser’s free CanKing CAN bus monitor and general-purpose diagnostic tool to check the CAN connections. Apart from that, all the software has been developed by myself in-house. For the hardware, we turned to Kvaser, whose CAN interfaces I have used for more than 10 years. This time the requirement was for data loggers, so we have opted for Kvaser Memorator Pro and Memorator Light models, which are proving very easy to use.”

The Kvaser Memorator Light data logger has a fifo function, whereby data is held in a circular buffer and the oldest data is overwritten when the buffer becomes full. This means that data logging systems like these can be left on the vehicle for a prolonged period and if something happens that requires further investigation, the most recent information is available for analysis. Notes Rosengren: “We use the Memorator Pro to capture a particular behaviour when we try to replicate the conditions that bring it about. “

The data loggers are attached to the vehicle network using a standard J1939 connector and sit in a compartment at the front of the bus. Occasionally, it is necessary to simultaneously gather data from a J1587 network alongside the standard J1939 one, so a Kvaser Linx J1587 adapter is attached. Kvaser’s data loggers are ‘listen only’, meaning that their presence on the vehicle’s network has no impact on the messages being sent and received. All Nobina’s Kvaser devices have been supplied by Kvaser technical associate, Accurate Technologies Sweden AB, an independent global supplier of control system development tools.

For Rosengren, public transport is someway from his previous role as electrical architecture lead at Swedish supercar manufacturer, Koenigsegg Automotive AB. At Koenigsegg, where he was responsible for developing the hardware and software for the sports car’s control systems. Change beckoned for personal reasons; Nobina’s head offices are located closer to Rosengren’s home. With a background in vehicle engineering and his R&D experience, Rosengren is well placed to help prepare Nobina’s fleet for the future, whether that fleet is diesel, hybrid or fully electric, driven or autonomous. And Kvaser’s data logging systems will be there to help.